In a letter to Homeland Security Secretary Janet Napolitano obtained by BuzzFeed, the conservative charged that "using the sequester as an excuse to initiate this unprecedented mass release of illegal immigrants is a patently political and deliberate move that undermines law enforcement and places our nation's security at risk."

In the letter, she asks how much money the department will save by monitoring the immigrants outside of jails, how many of the immigrants had been charged with or convicted of violent crimes, among a number of other questions.

Black sits on the on the House Ways and Means oversight subcommittee.

The department has maintained that the released immigrants are "low-risk." In a briefing Wednesday, White House press secretary Jay Carney said the White House was not consulted about the decision.

On Wednesday, the Associated Press reported that a senior Homeland Security Department official retired Tuesday after the decision had been made to release some illegal immigrants.